1. Field of the Invention
The present invention relates to a recording sheet suitably used in ink jet recording, a method of manufacturing and storing the recording sheet, and an ink jet recording method using the recording sheet.
2. Related Art
A recording medium conventionally used in ink jet recording includes a recording paper composed of a base layer having a coated layer formed thereon which contains fine powder silica and a water-soluble binder such as polyvinyl alcohol as disclosed in Japanese Patent Examined Publication No. Hei 3-26665, a glossy paper composed of a cast coated paper having a film formed thereon which contains polyvinyl alcohol having a degree of saponification of 50-90 mol % and a bridging agent as disclosed in Japanese Patent Examined Publication No. Hei 3-25352, and further a recording sheet for use with an overhead projector (OHP) composed of a polyester film having a hydrophilic film composed of water-soluble polyvinyl alcohol having a degree of saponification of 70-90 mol % as disclosed in Japanese Patent Unexamined Publication No. Sho 60-220750.
Recently, with the improvements in ink jet recording apparatuses such as an increase in recording speed, multi-color printing and the like, an ink jet recording medium is required to provide higher and wider characteristics. That is, the following characteristics are required to be simultaneously satisfied:
(1) higher ink absorbing capability (larger absorbing capacity and shorter absorbing time); PA1 (2) capability of formed dots to have higher optical density and the periphery of the dots not to become obscure; PA1 (3) capability of formed dots to have a shape approximating a perfect circle with a smooth periphery; PA1 (4) capability of image characteristics to be less changed by temperature and humidity and prevention of curling due to such conditions; PA1 (5) prevention of blocking; and PA1 (6) capability of an image to be stably retained for a long time without deteriorating quality (in particular, in the environment of high temperature and high humidity), and the like.
There is also a need for a recording sheet excellent in transparency such as a recording sheet for OHP and a recording paper having a surface glossiness.
As a recording speed is increased, an image has an increased density, and a ratio of images printed with colors is increased, a serious problem arises in that the quality of the image is lowered due to defective fixing of ink. More specifically, since a recording sheet has an insufficient ink absorbing capability, an image is made dirty and a thickness of ink is made uneven due to the flooding of ink at the portion of the recording sheet where the image has a high density, that is, where a large amount of ink is ejected. Further, in the case of color printing, colors are made dirty by the mixing of colors at the boundaries of different colors. To cope with the above problems, there is conventionally employed a method of compensating an insufficient ink absorbing capability by increasing a thickness of a covering layer (ink receiving layer). In this case, however, there is a problem that a recording sheet is liable to be curled by the change of temperature and humidity. To restrict the occurrence of curling, conventionally, there is often employed such methods as to form the same covering layer on both surfaces of a base member and form a curling prevention layer on the surface of a recording sheet opposite to a recording surface.
As a recording speed is increased, a recording apparatus employing an ink jet recording system has been widely used which continuously carries out recording by using cut recording sheets loaded on a paper feed tray. A generally used example of this type of the recording apparatus comprises a paper feed tray on which cut recording sheets can be loaded and transportation means for separating one of the recording sheets loaded on the paper feed tray by contacting at least one surface of the recording sheet and transporting the separated recording sheet from the paper feed tray to a recording unit.
When the aforesaid recording apparatus is used, a recording sheet is further required to provide such a performance that the recording sheet does not move obliquely while it is being transported, the recording sheet is not jammed, and loaded recording sheets can be easily separated.
In particular, since the transparent recording sheet and the recording sheet having a glossy surface mentioned above must be provided with a covering layer as transparent as possible to restrict the dispersed reflection of light incident on a recording surface, it is difficult to obtain these recording sheet satisfying the above characteristics. Thus, it has not been examined to further provide these recording sheets with transporting characteristics in addition to the above characteristics.